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Hee-Seon Kim1 *, Min-Kyung Ji2 *, Woo-Hyung Jang1 *, Khurshed Alam,3 Hyun-Seung Kim,4 Hoon-Sung Cho,3 Hyun-Pil Lim1 1Department of Prosthodontics, School of Dentistry, Chonnam National University, Gwangju, Republic of Korea; 2Optoelectronics Convergence Research Center, Chonnam National University, Gwangju, 61186, Republic of Korea; 3Department of Materials Science and Engineering, Chonnam National University, Gwangju, 61186, Republic of Korea; 4Department of Division of New Projects, KJ Meditech Co, Ltd, Gwangju, 61009, Republic of Korea*These authors contributed equally to this workCorrespondence: Hyun-Pil LimDepartment of Prosthodontics, School of Dentistry, Chonnam National University, Gwangju, 61186, Republic of KoreaTel +82-10-2645-7528Fax +82-62-530-5577Email mcnihil@jnu.ac.krHoon-Sung ChoDepartment of Materials Science and Engineering, Chonnam National University, Gwangju, 61186, Republic of KoreaTel +82-10-8545-2816Fax +82-62-530-1717Email cho.hoonsung@jnu.ac.krPurpose: This paper presents a technique for developing a novel surface for dental implants using a combination of nitriding and anodic oxidation, followed by the deposition of graphene oxide using atmospheric plasma. The effects of various surface treatments on bacterial adhesion and osteoblast activation were also evaluated.Methods: CP titanium (control) was processed into disk-shaped specimens. Nitriding was conducted using vacuum nitriding, followed by anodic oxidation, which was performed in an electrolyte using a DC power supply, to form the novel “mulberry surface.” Graphene oxide deposition was performed using atmospheric plasma with an inflow of carbon sources. After analyzing the sample surfaces, antibacterial activity was evaluated using Streptococcus mutans and Porphyromonas gingivalis bacteria. The viability, adhesion, proliferation, and differentiation of osteoblasts were also assessed. Analysis of variance (ANOVA) with Tukey’s post-hoc test was used to calculate statistical differences.Results: We observed that the mulberry surface was formed on samples treated with nitriding and anodic oxidation, and these samples exhibited more effective antibacterial activity than the control. We also found that the samples with additional graphene oxide deposition exhibited better biocompatibility, which was validated by osteoblast adhesion, proliferation, and differentiation.Conclusion: The development of the mulberry surface along with graphene oxide deposition inhibits bacterial adhesion to the implant and enhances the adhesion, proliferation, and differentiation of osteoblasts. These results indicate that the mulberry surface and graphene oxide deposition together can inhibit peri-implantitis and promote osseointegration.Keywords: nitriding, anodic oxidation, atmospheric plasma, biofilm formation, osteoblasts

Titanium implants have been widely used as one of the most effective treatments of bone defects. However, the lack of osteogenesis and bacteria-resistant activities result in high infection and loosening rates of titanium implants. Anodic oxidation could easily construct titanium dioxide nanotubes (TNTs) array on the surface of titanium, and the rough surface of TNTs is beneficial to the growth of osteoblast-related cells on the surface. And TNTs could be excellent drug carriers because of their single-entry tubular hollow structure. In this review, we aim at detailing the application of TNTs as drug carriers in the field of bone implants. Starting from the topography of TNTs, we illustrated the biological activity of the TNTs surface, the drugs for loading in TNTs, and the controlled and responsive release strategies of drug-loaded TNTs, respectively. At the end of this review, the shortcomings of TNTs as the drug carrier in the field of bone implants are discussed, and the development direction of this research field is also prospected.

An innovative low-cost method of aluminium surface treatment to obtain stable superhydrophobic properties is presented. An aluminium anodising method was combined with surface abrasive blasting as ...

The identity of the mechanisms of anodic oxide films formation on silicon, silicon carbide, and silicon nitride is proved, which can be used as the basis for the General theory of anodic oxidation of these materials. The processes of galvanostatic anodic oxidation of Si, SiC and Si3N4 in the intervals of linear dependence of the formation voltage on time proceed with activation control. The limiting stages in all cases are the anodic reactions of the formation of intermediate SiO monoxide. Preference should be given to electrolytes with lower values of the potential environmental hazard criterion of the electrolyte, which have a higher degree of environmental safety.

The development of affordable, low-iridium-loading, scalable, active, and stable catalysts for the oxygen-evolution reaction (OER) is a requirement for the commercialization of proton-exchange membrane water electrolyzers (PEMWEs). However, the synthesis of high-performance OER catalysts with minimal use of the rare and expensive element Ir is very challenging and requires the identification of electrically conductive and stable high-surface-area support materials. We developed a synthesis procedure for the production of large quantities of a nanocomposite powder containing titanium oxynitride (TiON x ) and Ir. The catalysts were synthesized with an anodic oxidation process followed by detachment, milling, thermal treatment, and the deposition of Ir nanoparticles. The anodization time was varied to grow three different types of nanotubular structures exhibiting different lengths and wall thicknesses and thus a variety of properties. A comparison of milled samples with different degrees of nanotubular clustering and morphology retention, but with identical chemical compositions and Ir nanoparticle size distributions and dispersions, revealed that the nanotubular support morphology is the determining factor governing the catalyst's OER activity and stability. Our study is supported by various state-of-the-art materials' characterization techniques, like X-ray photoelectron spectroscopy, scanning and transmission electron microscopies, X-ray powder diffraction and absorption spectroscopy, and electrochemical cyclic voltammetry. Anodic oxidation proved to be a very suitable way to produce high-surface-area powder-type catalysts as the produced material greatly outperformed the IrO2 benchmarks as well as the Ir-supported samples on morphologically different TiON x from previous studies. The highest activity was achieved for the sample prepared with 3 h of anodization, which had the most appropriate morphology for the effective removal of oxygen bubbles.

A 3C production uses Al–Zn–Mg alloy as the material of its housings which appeared with black lines on the surface after anodic oxidation treatment. Through appearance observation, 3D outline scanning, SEM section observation, EDS composition test, inclusion analysis, and chemical composition, the cause of the black lines and the solution was brought forward. The results show that the black lines were induced by particles rich in Ti and B in the anodic oxidation film along the extrusion direction. The particles were TiB2 which came from the grain refiner Al–Ti–B during the Al–Zn–Mg alloy manufacture.

The paper deals with the complaint between the manufacturer and the customer. The object of the dispute is a damaged stroller construction made by welding Al-Mg-Si aluminum alloy profiles with the final surface layer produced by anodic oxidation. The aim of the analysis is to identify clearly the causes of breaking the aluminum structure using fractographic and metallographic techniques.

La industria del café soluble genera aguas residuales que contienen mezclas complejas de sustancias difíciles de degradar. Su mineralización no es completamente efectiva mediante tratamientos convencionales. En este trabajo, se estudia un proceso secuencial de electrocoagulación - oxidación anódica (EC-OA) como alternativa de tratamiento. En específico, se evaluó experimentalmente el efecto del material del electrodo (v.g., dos ánodos (grafito y Diamante Dopado con Boro (DDB)) y seis cátodos (acero inoxidable, titanio, hierro, aluminio, grafito y DDB)) y del electrolito de soporte (NaCl o Na2SO4) sobre el rendimiento de degradación en términos de la reducción de color y de la demanda química de oxígeno (DQO), así como de la formación de sólidos suspendidos totales (SST). Los resultados obtenidos fueron comparados con la última regulación ambiental colombiana. Adicionalmente, para cada caso, se realizó un análisis integral de los costos operacionales. Toda la información anterior permitió seleccionar dos sistemas de electrodos como los más prometedores para la etapa de OA: DDB-acero inoxidable + Na2SO4: muy eficiente pero costoso (reducción de DQO = 75% y 12 USD/m3) y grafito-acero inoxidable + NaCl: menos eficiente y más económico (reducción de DQO = 67% y 7 USD/m3). The industry of soluble coffee generates wastewater containing complex and hard to degrade mixtures of different substances. Their mineralization is not completely effective through conventional treatment methods. In this work, as a treatment alternative, a sequential Electrocoagulation-Anodic Oxidation (EC-AO) process is studied. The effect of electrode material (v.g., two different anodes (graphite and Boron-Doped Diamond (BDD)) and six different cathodes (stainless steel, titanium, iron, aluminum, graphite and BDD)) and of support electrolyte (NaCl or Na2SO4) on degradation performance of AO, in the terms of color and chemical oxygen demand (COD) reduction, as well as Total Suspended Solids (TSS) formation and pH, were experimentally tested. The obtained results were compared with the most recent Colombian environmental regulation. Additionally, for each case, a comprehensive operational costs analysis was performed. All the above information allowed to select two electrode systems as the most promising for the AO step: BDD-stainless steel + Na2SO4: very efficient but expensive (reduction of COD = 75% and 12 USD/ m3) and graphite-stainless steel + NaCl: less efficient and more economic one (reduction of COD = 67% and 7 USD/m3).

This study used boron-doped diamond electrode on niobium substrate (Nb/boron-doped diamond [BDD]) for the anodic oxidation of landfill leachate in a batch reactor. Raw leachate and biologically pre...

The lack of suitable cathodes is one of the key reasons that impede the development of aqueous zinc-ion batteries. Because of the inherently unsuitable structure and inferior physicochemical proper...

In this study, the main goal is to determine the effects of the variable anodic oxidation process parameters on the hardness and wear properties of the AA7075-T6 alloy, which is widely used in the gun industry, automotive, aircraft, and space industry. Samples obtained using the process parameters designed by the Taguchi method were subjected to various experiments and the findings obtained from these experiments were compared with S/N graphs determined using ANOVA analysis. As a result of these findings, it was determined that different coating thickness, hardness and wear resistance were obtained by varying the anodic oxidation process parameters. The highest oxide layer thickness obtained was determined as 70.63 µm. In addition, the oxide layer formed by the anodic oxidation process has significantly increased the hardness and wear resistance of the AA 7075-T6 alloy. Also, as a result of the experiments and ANOVA analysis, it was determined that the oxide layer obtained with the parameters of 22V constant voltage, 1.3A/dm2 current density, 2°C temperature, 140 minutes of processing time will have the superior wear performance.

To improve the growth of hydroxyapatite (HA) coating on the Ti-6Al-4V substrate, a solution containing calcium acetate (CA), calcium glycerophosphate hydrate (Ca-GP), and different concentrations of Na2SO4 as the electrolyte for anodic treatment was investigated in this study. The results found that the anodic method is suitable for Ti-6Al-4V titanium alloy to form an HA coating with the electrolyte consisting of CA, Ca-GP, and Na2SO4. These anodic oxide films display a greater rough structure on the surface of films and the addition of Na2SO4 into the electrolyte during the anodic oxidation process contributes to an increase in the atomic ratio (at%) of Ca in the anodic film. These Ca-containing films are considered bioactive and tend to dissolve into simulated body fluid (SBF) solution and then enhance the degree of the supersaturation of SBF solution with respect to the apatite. Therefore, increasing the concentration of Na2SO4 increases the growth of HA following immersion into SBF. In addition, prior to immersion into SBF solution, the contact angle measurement using an SBF droplet was also investigated for HA growth. The results indicate that when the contact angle of anodic surface is larger, the formation time of HA coating is shorter and it will easily grow a thicker HA.

The optimisation process of the orthogonal experiment was designed by Taguchi experiment. Nanopores structure was prepared on the surface of stainless steel by anodic oxidation in the nitric acid s...

Surface morphology and composition of anodized Ti-15Zr-4Nb-4Ta alloys with nanotube were examined by using X-ray diffractometry and analytical scanning electron microscopy. The Ti alloy consisted of α and β phases. Anodizing to form nanotube on the Ti alloy was carried out using electrolyte of 0.2 wt.% NH4F and 2 Vol.% H2O in ethylene glycol under different potential at from 30 to 60V. SEM observation showed that nanotubes were vertically aligned on surface of the Ti alloy. Inner diameter of these nanotubes varied from 45 to 127 nm with increasing applied potential to the specimen from 30 to 60 V. Surface of the Ti alloy with nanotube was ragged due to the difference in dissolution rate of the internal structure of α and β phases.

The ceramic surface treatment of aluminum alloy is an important means to improve the mechanical properties and corrosion resistance of aluminum alloy.This paper focuses on the process and research status of aluminum alloy anodic oxidation technology and aluminum alloy micro-arc oxidation technology and analyzes the future development direction.

By applying a three-step anodic oxidation method followed by etching and pore widening treatment, etched micro-/submicroscale pits of ∼2 μm and ∼230 nm as well as anodized nanopores of ∼70 nm are c...

Electrochemical exfoliation of graphite stands out as a promising alternative to the existing methods for scalable graphene fabrication. However, factors governing the electrochemical process and the underlying mechanism are complex and how to effectively control the exfoliation process is far from completely clear despite many attempts in previous works. Herein, for the first time, capillary infiltration, anodic oxidation and their dependence on temperature were found to be critical in determining the electrolyte infiltration and the anodic oxidation process. On this basis, we achieved tuning of sheet dimensions (both thickness and lateral size) and surface chemistry of graphene by facilely controlling the temperature (5-95 °C). Four kinds of graphene materials featuring small size, porosity, water dispersibility and large size can be selectively fabricated in the same electrolyte system at different temperatures. Especially, low-temperature exfoliation results in high yields (99.5%) of small-sized graphene, which is a new breakthrough for electrochemical methods. The finding and associated mechanism of temperature's influence on both capillary infiltration and anodic oxidation not only deepen our understanding of the electrochemical exfoliation, but also make electrochemistry a versatile technique for graphene fabrication.

Becauseof the high strength-to-weight ratio and excellent corrosion resistance, titanium alloys are widely applied in marine industries. However, titanium alloys suffer from serious biofouling problems for their good biocompatibility. Slippery lubricant-infused porous surface (SLIPS) exerts a positive effect on inhibiting the attachment of marine microorganism. In this work, SLIPS was fabricated on TC4 (Ti-6Al-4V) alloys through anodic oxidation, 1H,1H,2H,2H,-perfluorooctyltriethoxysilane (POTS) modification and polyperfluoromethyl isopropyl ether (PFPE) infusion to improve the antifouling property of TC4 alloys. The antifouling effect of all coatings was investigated and compared to obtain the antifouling mechanism of SLIPS through recording the settlement of

A synthetic wastewater based on Algiers refinery real effluent was prepared and treated using anodic oxidation. Full factorial plan design was used to conduct the statistical analysis of the results. The aim of the study was to assess the interaction between current density (CD) and stirring degree (SD), and quantify their effects on chemical oxygen demand (COD) removal and electric energy specific consumption (EESC). With an initial COD of 487 mg/L, pH of 5.5 and 0.05 M of Na2SO4 as supporting electrolyte, it was found that a 55 rpm stirring degree variation led to a substantial gain in COD removal and energy consumption: 6% and 8.5 KWh/kg, respectively. Current density was found to have a different effect on removal efficiency within the applied stirring domain, and mass transport coefficient (km) is inversely correlated to energy consumption. A theoretical model describing the process was reviewed and the relation between concentration, hydrodynamics and applied current was emphasized. HIGHLIGHTS A simple empirical modeling to assess charge rate and mass transport rate balance (i.e. operating regime).; Lead anode was first applied for electro-oxidation of toluene.; Perspectives on the up-scaling approach taken and comparative data were discussed.; Theoretical modeling review.

This work concerns the development of a method of functionalization of the surface of the biomedical Ti–6Al–7Nb alloy by producing oxide nanotubes (ONTs) with drug-eluting properties. Shaping of the morphology, microstructure, and thickness of the oxide layer was carried out by anodization in an aqueous solution of 1 M ethylene glycol with the addition of 0.2 M NH4F in the voltage range 5–100 V for 15–60 min at room temperature. The characterization of the physicochemical properties of the obtained ONTs was performed using SEM, XPS, and EDAX methods. ONTs have been shown to be composed mainly of TiO2, Al2O3, and Nb2O5. Single-walled ONTs with the largest specific surface area of 600 cm2 cm−2 can be obtained by anodization at 50 V for 60 min. The mechanism of ONT formation on the Ti–6Al–7Nb alloy was studied in detail. Gentamicin sulfate loaded into ONTs was studied using FTIR, TG, DTA, and DTG methods. Drug release kinetics was determined by UV–Vis spectrophotometry. The obtained ONTs can be proposed for use in modern implantology as carriers for drugs delivered locally in inflammatory conditions.

Although diamond electrodes are widely used in the field of electroanalysis and sensing, their application in the field of environmental engineering has yet to be fully realized. Many research studies have considered their potential application in water and wastewater treatment, where the in-situ electrochemical process can avoid the need for chemical additives by facilitating the oxidation of pollutants on the electrode surface or mediated by electrochemically synthesized oxidants in solution. Diamond-based electro-oxidation can effectively treat a number of organic micropollutants and is now being evaluated for the abatement of perfluoroalkyl and polyfluoroalkyl substances, which pose health concerns and are ubiquitous recalcitrant environmental contaminants. To move implementation of diamond-based electro-oxidation forward, the integration of modifications and codopants to yield more advanced electrode materials needs to be further developed and understood. The progress and current strategies associated with diamond electrode modifications for perfluoroalkyl and polyfluoroalkyl substances abatement as well as future considerations are discussed.

How to improve the corrosion resistance and icing-delay ability of metal in practice is still a big challenge. Herein, a ZnO surface with superhydrophobicity was fabricated by combining anodic oxidation and surface modification on zinc substrate. The effects of topographies and chemical composition on surface wettability were discussed in detail. The water contact angle and roll-off angle on the optimal superhydrophobic ZnO surface is about 161.0° and 5°, respectively. The results reveal the self-cleaning property, the corrosion resistance and icing-delay ability of the as-prepared sample were improved due to the superhydrophobic treatment. The method adopted here is facile and the cost is low, which is believed to afford a new idea for the design and construction of superhydrophobic surface on metal-based materials and broaden its potential application in anti-corrosion and icing-delay fields.

Anodised titanium has a long history as a coating structure for implants due to its bioactive and ossified surface, which promotes rapid bone integration. In response to the growing literature on anodised titanium, this article is the first to revisit the evolution of anodised titanium as an implant coating. The review reports the process and mechanisms for the engineering of distinctive anodised titanium structures, the significant factors influencing the mechanisms of its formation, bioactivity, as well as recent pre- and post-surface treatments proposed to improve the performance of anodised titanium. The review then broadens the discussion to include future functional trends of anodised titanium, ranging from the provision of higher surface energy interactions in the design of biocomposite coatings (template stencil interface for mechanical interlock) to techniques for measuring the bone-to-implant contact (BIC), each with their own challenges. Overall, this paper provides up-to-date information on the impacts of the structure and function of anodised titanium as an implant coating in vitro and in/ex vivo tests, as well as the four key future challenges that are important for its clinical translations, namely (i) techniques to enhance the mechanical stability and (ii) testing techniques to measure the mechanical stability of anodised titanium, (iii) real-time/in-situ detection methods for surface reactions, and (iv) cost-effectiveness for anodised titanium and its safety as a bone implant coating., Anodised titanium, Anodic oxidation, Anodic layer, Titanium nanotube, Implant coating, Surface modification, Anodization, TiO2, Coating template stencil.

The anodic dissolution of aluminum is studied. A mechanism for the process is proposed and confirmed experimentally. As evidence for this mechanism, it is established that the Nernst–Peters equation can be used to calculate the equilibrium potential of the anodic oxidation of water, which allows determination of the real temperature in the reaction zone.

The AFM tip induced local anodic oxidation (LAO) nanolithography is capable of manufacturing nanometer scale structures and devices for future generation. Experimental studies of LAO on silicon sur...

Humidity sensors based on QCM (quartz crystal microbalance) have been developed using an anodized alumina thin‐film as a sensing material. An aluminum thin‐film is deposited on a silver‐co...

Modifying the geometric and surface parameters of oriented TiO2 nanotubes (NTs) is beneficial to the utilization of solar energy for chemical reactions, and this performance may be further improved. Thus, the effects of adding an ionic liquid (IL), 1-butylpiridinium chloride [BPy][Cl], and the effects of the water content and preparation conditions on the surface morphological, physicochemical, photocatalytic, and photoelectrochemical properties of TiO2 NTs were thoroughly examined and presented. The anodic oxidation of Ti foil in an organic electrolyte containing a small amount of [BPy][Cl] allowed for obtaining IL_NTs with a well-ordered structure, even at low voltages (10 V). Additionally, the application of [BPy][Cl] enabled one of the geometric parameters of the IL_NTs, namely, the diameter, to be tuned, whereas the length remained the same (i.e., control over the diameter was first noted). Improvements in the photocatalytic and photoelectrochemical activities of the IL_NTs in comparison with those o...

Superhydrophobic nanostructured TiO2 film was successfully fabricated on the Ti plate by anodic oxidation and lauric acid modification. By varying the applied voltage, TiO2 films with various nanostructures and colors were prepared. The water contact angles (WCA) on the modified TiO2 film increased as the applied voltage increased, and the highest WCA on the TiO2 nanovesuvianite film was about 161.23°. When the applied voltage was 5 V and 20 V, the obtained TiO2 nanopores and TiO2 nanotubes could be used to build two improved Cassie models for designing superhydrophobic surface. Moreover, the superhydrophobic TiO2 film showed good anti-fouling property, particularly it could maintain superhydrophobicity both when immersed in and taken out from the organic solvents. The superhydrophobic film could be changed into superhydrophilic under ultraviolet (UV) irradiation, and the superhydrophilic film recovered to hydrophobic or superhydrophobic gradually at 60 °C in the dark. Additionally, the superhydrophilic film showed underwater superoleophobicity, which exhibited excellent anti-fouling property by degrading the oil under UV light.

Developing processes that allow partial oxidation of light alkanes (C1–C4) to more valuable oxygenates is important from both industrial and academic perspectives. In this study, quantum mechanics ...

An efficient and reliable electrochemical generator of hypervalent iodine reagents has been developed. In the anodic oxidation of iodoarenes to hypervalent iodine reagents under flow conditions, the use of electricity replaces hazardous and costly chemical oxidants. Unstable hypervalent iodine reagents can be prepared easily and coupled with different substrates to achieve oxidative transformations in high yields. The unstable, electrochemically generated reagents can also easily be transformed into classic bench-stable hypervalent iodine reagents through ligand exchange. The combination of electrochemical and flow-chemistry advantages largely improves the ecological footprint of the overall process compared to conventional approaches.

The cyanidation process is used for the recovery of gold and silver from their ores. However, during cyanidation, some of the copper minerals present are also dissolved, resulting in the pr...

The nanoscaled profiling of a silicon 5 (111) n-type substrate surface is studied by the local anodic oxidation (LAO). Varying the voltage pulse amplitude from 5 to 12.5 V and the humidity from 30 ± 1 to 70 ± 1% during the LAO is a promising way to form oxide structures with heights from 0.5 ± 0.3 to 2.1 ± 0.1 nm and profiled structures with depths from 0.4 ± 0.3 to 1.5 ± 0.2 nm on the substrate. The results can be applied to the development of technological processes of the element base of silicon-based nanoelectronics using the probe nanotechnologies.

An ultrasonic-assisted electrochemical mechanical polishing (UAECMP) technique that combines ultrasonic vibration and electrochemical mechanical polishing (ECMP) is proposed. The effect of ultrasonic vibration on the anodic oxidation rate of a 4H-SiC (0001) surface was studied, and it was confirmed that ultrasonic vibration significantly enhanced the anodic oxidation of SiC. Compared with conventional anodic oxidation, the oxidation rate increased by about 34% with ultrasonic assistance (UA) in the initial oxidation stage, and by about 11% during subsequent anodic oxidation. In addition, the oxidation can be promoted continuously with increasing oxidation time owing to the porous structure of the oxide layer. UAECMP is very promising as an efficient finishing technique for SiC surfaces. Keywords: Silicon carbide, Ultrasonic-assisted electrochemical mechanical polishing, Ultrasonic-assisted anodic oxidation, Ultrasonic vibration

A novel integrative bioinspired surface with wettable patterns and gradient (WPGS) is proposed for fog collection via a novel anodic oxidation strategy. We study the water collection behaviors on WPGS with different parameters. Quantitative force analysis is presented, providing evidence for the underlying mechanism leading to the directional motion of the droplet, which is consistent with the experimental results. Such a surface can not only improve the fog droplet capture performance effectively owing to wettable patterns but also accelerate surface regeneration by taking full advantage of the cooperation of multidriving forces, leading to a further fog collection enhancement.

The anodic oxidation rate of silicon-on-insulator films fabricated by hydrogen transfer is studied as a function of the temperature of subsequent annealing. It is established that the oxidation rate of transferred silicon-on-insulator films is five times lower compared to the oxidation rate of bulk single-crystal silicon samples. The oxidation rate increases, as the annealing temperature is elevated in the range 700–1100°C and as the depth of gradually removed anode-oxidized layers is increased. The results obtained in the study are attributed to an increase in the efficiencies of the anodic current and oxygen–silicon interatomic interaction due to the annealing of defects and due to release of hydrogen from the bound state, respectively. The formation of hydrogen bubbles in the surface region of silicon due to the diffusion of hydrogen, released in the process of the oxidation reaction, towards micropores in the silicon-on-insulator layer is detected.

2198 and 5A90 Al-Li alloys were anodized with a constant DC potential in 18%H2SO4 solution (Solu.A) and the mixture solution of 18%H2SO4+5%C2H2O4 (Solu.B) at room temperature. 12 and 11 V was optimized as the applied oxidation potential for 2198 and 5A90 alloys, respectively. Cross-sectional morphology, surface morphology and elements distribution of anodic oxidation coatings were observed by scanning electron microscope equipped with energy dispersive X-ray analysis (SEM/EDX). Corrosion resistance was tested by potentiodynamic polarization plot in 3.5%NaCl solution. The results showed that the thicknesses of coatings obtained at the selected potential in Solu.A and Solu.B were about 50 μm/110 μm for 2198 alloy and 80 μm/110 μm for 5A90 alloy. In both solutions, anodic oxidation coatings of 2198 alloy were primarily composed of Al oxides; those of 5A90 alloy were mainly consisted of Al oxides and a small amount of Mg oxides. The results of potentiodynamic polarization showed that anodic oxidation coatings of 2198 and 5A90 Al-Li alloys had better corrosion resistances than that of untreated alloys.